Method for preparing highly-reliable multilayer solid aluminum electrolytic capacitor

ABSTRACT

A method for preparing a stacked solid aluminum electrolytic capacitor is disclosed. The method includes preparation of a plurality of cores, stacking and fixing of the plurality of cores in a case and encapsulation of the case. The core is prepared through the following steps. An I-shaped aluminum foil is divided into an anode part and a cathode part by applying an insulating blocking tape, where the cathode part includes a dielectric layer, which is subjected to formation. A conductive polymer layer is formed on a surface of the cathode part, and is then impregnated with conductive colloidal graphite followed by drying to form a conductive carbon paste layer. The conductive carbon paste layer is impregnated with a conductive silver paste followed by drying to form a conductive silver paste layer. After that, a core is obtained.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 18/180,607, filed on Mar. 8, 2023, now pending, which is a continuation of International Patent Application No. PCT/CN2022/120615 with a filing date of Sep. 22, 2022, designating the United States, and further claims the benefit of priority from Chinese Patent Application No. 202210902877.4, filed on Jul. 29, 2022. The content of the aforementioned application, including any intervening amendments thereto, is incorporated herein by reference in its entirety.

TECHNICAL FIELD

This application relates to solid aluminum electrolytic capacitors, and more particularly to a method for preparing a highly-reliable multilayer solid aluminum electrolytic capacitor.

BACKGROUND

Multilayer solid aluminum electrolytic capacitors employ a conductive polymer material as the solid electrolyte, and have a core package structure formed by lamination of multi-layer cores in parallel and a shape suitable for the surface mounting. Compared with the traditional liquid aluminum electrolytic capacitors, they are superior in terms of size, basic electrical performance, service life, frequency impedance and temperature characteristics, environmental protection and safety.

The existing multilayer solid aluminum electrolytic capacitors are generally prepared through the following steps: dividing a formed foil into an anode zone and a cathode zone with a separator; successively forming a conductive polymer solid electrolyte layer, a conductive carbon paste layer, and a silver paste layer on a surface of the cathode zone to form a capacitor core; stacking multiple capacitor cores in parallel, and connecting the stacked capacitor core structure to an external lead frame to lead out the anode and cathode; encapsulating the stacked capacitor core structure with epoxy resin; and bending the leads exposed outside the resin case to form the external terminals.

Although the above-mentioned resin encapsulation is suitable for low-cost and large-scale automated industrial production, it is non-hermetic, and thus it is easy for moisture, corrosive gases, or liquids to enter the capacitor under harsh conditions such as high temperature and high humidity, resulting in deterioration or even failure of the product. Furthermore, since the organic resin is in direct contact with the cores, it is easy to enter the gap between the cores during injection molding, which will result in extrusion deformation of the cores, causing an increase in the leakage current and equivalent series resistance (ESR), and even delamination and capacitor failure. Moreover, the stress produced by the shrinkage of the resin encapsulation material during curing will also result in performance deterioration or even failures. The above-discussed defects limit the application of conventional resin-encapsulated multilayer solid aluminum electrolytic capacitors, especially in complex environments and those fields with high reliability requirements. Therefore, it is urgently needed to design and develop a highly-reliable multilayer solid aluminum electrolytic capacitor to solve the above problems.

SUMMARY

To overcome the above-mentioned technical problems in the prior art, the present disclosure provides a highly-reliable multilayer solid aluminum electrolytic capacitor and a method for preparing the same.

Technical solutions of this application are described below.

The disclosure provides a method for preparing the aforementioned multilayer solid aluminum electrolytic capacitor, comprising:

-   -   (S1) cutting a formed aluminum foil to obtain an I-shaped         aluminum foil; wherein the I-shaped aluminum foil comprises a         rectangular connection part;     -   (S2) dividing the I-shaped aluminum foil into an anode part and         a cathode part by applying an insulating blocking tape to the         rectangular connection part, wherein the cathode part comprises         a dielectric layer, and the anode part is provided with one or         more circular through holes;     -   (S3) subjecting the dielectric layer to formation;     -   (S4) forming a conductive polymer layer on a surface of the         cathode part;     -   (S5) impregnating the conductive polymer layer with conductive         colloidal graphite followed by drying to form a conductive         carbon paste layer;     -   (S6) impregnating the conductive carbon paste layer with a         conductive silver paste followed by drying to form a conductive         silver paste layer, such that a core is obtained;     -   (S7) repeating steps (S1)-(S6) to obtain a plurality of cores;     -   (S8) stacking and fixing the plurality of cores in a case to         form a semi-finished capacitor; and     -   (S9) placing a cover plate on the case; and sealedly connecting         the cover plate with the case to produce the stacked solid         aluminum electrolytic capacitor.

In some embodiments, step (S8) comprises:

-   -   (S8-1) penetrating a bottom of the case with an anode electrical         connection part and a cathode electrical connection part;         wherein the cathode electrical connection part is applied with a         conductive silver adhesive; and the anode electrical connection         part is provided with one or more cylindrical positioning pins,         and the one or more cylindrical positioning pins are in         one-to-one correspondence with the one or more circular through         holes on the anode part of the core;     -   (S8-2) bonding the cathode electrical connection part with a         first cathode part of a first core; and passing the one or more         cylindrical positioning pins through the one or more circular         through holes on a first anode part of the first core;     -   (S8-3) repeating step (S8-2) to complete the stacking of the         plurality of cores; and bonding cathode parts of the plurality         of cores through the conductive silver adhesive followed by         curing to obtain a cathode of the stacked solid aluminum         electrolytic capacitor; and     -   (S8-4) inserting a rivet into a hole of each of one or more         cylindrical positioning pins; and fixing the rivet, the one or         more cylindrical positioning pins, and anode parts of the         plurality of cores through ultrasonic welding to obtain an anode         of the stacked solid aluminum electrolytic capacitor.

In some embodiments, the dielectric layer is provided on at least one side surface of the cathode part.

In some embodiments, the cover plate is sealedly connected with the case by parallel seam welding.

In some embodiments, the case comprises an anode chamber and a cathode chamber respectively matching the anode part and the cathode part of the core in shape.

In some embodiments, the method further comprise:

-   -   filling the anode chamber of the case with an insulating sealant         followed by curing.

Compared with the prior art, this application at least has the following beneficial effects.

-   -   (1) In this application, an inorganic encapsulation case is         adopted, which is formed by welding a case body with a cover         plate. Compared with the traditional resin encapsulation case,         the inorganic encapsulation case has higher air tightness, and         is more suitable for applications in complex environments and in         those fields with high reliability requirements.     -   (2) In this application, a gap is left between the encapsulation         case and the core, preventing the extrusion deformation of the         core during the injection molding process and eliminating the         stress generated by shrinkage of the plastic encapsulation         material during curing. Therefore, the encapsulation process         will not cause physical damage to the core, ensuring the         performance reliability of the core.     -   (3) In this application, a ceramic case with an I-shaped inner         cavity is adopted to match the I-shaped core. The anode part of         the core is led out by a riveting-welding method, and the anode         part of the core is filled with an insulating sealant for         secondary fixation and protection, which can effectively clamp         and fix the core, preventing the delamination caused by poor         welding of the anode and enhancing the core-package bonding         stability.

BRIEF DESCRIPTION OF THE DRAWINGS

To illustrate the technical solutions in the embodiments of the present disclosure or in the prior art more clearly, the accompanying drawings needed in the description of the embodiments or prior art will be described briefly below. Apparently, presented in the accompanying drawings are only some embodiments of the present disclosure. Other drawings may be obtained by one of ordinary skill in the art without paying any creative effort based on these drawings.

FIG. 1 is a schematic diagram of a solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 2 is a sectional view of the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a semi-finished solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of a core of the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of a rivet of the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of a case of the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of a cover plate of the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of an anode electrical connection part of the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 9 is a side view of the anode electrical connection part of the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 10 is a schematic diagram of a cathode electrical connection part of the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 11 is a side view of the cathode electrical connection part of the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure;

FIG. 12 is a flow chart illustrating a method for preparing the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure; and

FIG. 13 is a flow chart of step (S8) in the method of preparing the solid aluminum electrolytic capacitor according to an embodiment of the present disclosure.

In the drawings: 1, core; 11, anode part; 12, cathode part; 13, rectangular connection part; 14, insulating blocking tape; 15, circular through hole; 2, rivet; 21, circular rivet head; 22, cylindrical rivet pin; 3, case; 31, first side plate; 32, second side plate; 33, bottom plate; 34, blocking plate; 35, anode electrical connection part; 351, anode tongue portion; 3511, rectangular portion; 3512, cylindrical positioning pin; 352, anode connecting portion; 3521, anode ring protrusion; 353, anode terminal portion; 36, cathode electrical connection part; 361, cathode tongue portion; 362, cathode connecting portion; 3621, cathode ring protrusion; 363, cathode terminal portion; 37, rectangular metal ring; 4, cover plate; 41, protrusion; and 5, solid aluminum electrolytic capacitor.

DETAILED DESCRIPTION OF EMBODIMENTS

The technical solutions in the embodiments will be described clearly and completely below with reference to the accompanying drawings. Obviously, described below are merely some embodiments of the present disclosure, which are not intended to limit the present disclosure. Based on the embodiments provided herein, all other embodiments obtained by one of ordinary skill in the art without paying any creative work shall fall within the scope of the present disclosure.

Referring to FIGS. 1-13 , this application provides a highly-reliable multilayer solid aluminum electrolytic capacitor, which includes a plurality of cores 1, a rivet 2, a case 3, and a cover plate 4. The plurality of cores 1 are stacked in sequence, and fastened in the case 3 through the rivet 2 to form a semi-finished capacitor. The semi-finished capacitor is covered by the cover plate 4 and sealed to form a multilayer solid aluminum electrolytic capacitor 5.

Each of the plurality of cores 1 has an axially symmetrical I-shaped structure, and includes an anode part 11 and a cathode part 12. A rectangular connection part 13 is connected between the anode part and the cathode part 12. A width of the rectangular connection part 13 is smaller than that of the anode part 11 and the cathode part 12. Upper and lower surfaces and two side surfaces of the rectangular connection part 13 is coated with an insulating blocking adhesive to form an insulating blocking tape 14. The anode part 11 is provided with two circular through-holes 15 fitting the rivet 2. The cathode part 12 consists of a formed foil, a conductive polymer layer, a conductive carbon paste layer, and a conductive silver paste layer successively arranged from inside to outside.

The case 3 includes two first side plates 31, two second side plates 32, and a bottom plate 33. A length of the two first side plates 31 is larger than that of the two second side plates 32. A square open structure is enclosed by the two first side plates 31, the two second side plates 32, and the bottom plate 33. Inner side surface of the two first side plates 31 are each provided with one blocking plates 34, and two blocking plates 34 are arranged symmetrically. The two blocking plates 34 are connected to the bottom plate 33. The two blocking plates 34 are configured to divide an inner cavity of the case 3 into an anode chamber and a cathode chamber matching of the core 1 in shape. An anode electrical connection part 35 and a cathode electrical connection part 36 are penetratingly arranged on the bottom plate 33. The anode part 11 of the core 1 is electrically connected to the anode electrical connection part 35 through the rivet 2, and the cathode part 12 of the core 1 is electrically connected to the cathode electrical connection part 36. A rectangular metal ring 37 is fixedly arranged on an edge of an opening of the case 3.

Specifically, the rivet 2 includes a circular rivet head 21 and a cylindrical rivet pin 22 connected with each other, and the cylindrical rivet pin 22 matches with the circular through hole 15. The diameter of the circular rivet head 21 is larger than the diameter of the cylindrical rivet pin 22, and the end of the cylindrical rivet pin 22 away from the circular rivet head 21 is tapered.

Specifically, the edge of one side of the cover plate 4 near the case 3 is provided with a protrusion 41 matching with the rectangular metal ring 37, and the cover plate 4 is fixed through fitting between the protrusion 41 and the rectangular metal ring 37 by welding.

Specifically, the anode electrical connection part 35 includes an anode tongue portion 351, an anode connection portion 352, and an anode terminal portion 353 connected vertically in sequence. The anode tongue portion comprises a rectangular portion. A side of the rectangular portion 3511 away from the anode connection portion 352 is provided with a pair of cylindrical positioning pins 3512 matching with the pair of circular through holes 15. The rectangular portion 3511 is embedded in and flush with an inner surface of the bottom plate 33. An anode ring protrusion 3521 is provided at a middle of the anode connection portion 352. The anode terminal portion 353 is embedded in and flush with the outer surface of the bottom plate 33.

The cathode electrical connection part 36 includes a cathode tongue portion 361, a cathode connection portion 362, and a cathode terminal portion 363 connected vertically in sequence. The cathode tongue portion 361 is rectangular, and is embedded in and flush with the inner surface of the bottom plate 33. A cathode ring protrusion 3621 is provided at a middle of the cathode connection portion 362. The cathode terminal portion 363 is embedded in and flush with the outer surface of the bottom plate 33.

Specifically, the length of the rectangular connection part 13 is 10-30% of the total length of the core 1.

Specifically, a height of each of the two blocking plates 34 is equal to a height of each of the two first side plates 31, and a width of each of the two blocking plates 34 is 10-30% of the width of the bottom plate 33.

Specifically, the two first side plates 31, the two second side plates 32, the bottom plate 33, and the two blocking plates 34 are all made of alumina ceramic, and the rectangular metal ring 37 is made of a Kovar alloy.

Specifically, a portion of each of the anode terminal portion 353 and the cathode terminal portion 363 extending out of the case 3 is coated with a tin coating.

In a second aspect, this application provides a method for preparing the highly-reliable multilayer solid aluminum electrolytic capacitor, which includes the following steps.

-   -   (S1) A formed aluminum foil is cut to obtain an I-shaped         aluminum foil, where the I-shaped aluminum foil includes a         rectangular connection part 13.     -   (S2) The I-shaped aluminum foil is divided into an anode part         and a cathode part by applying an insulating blocking tape 14 to         the rectangular connection part 13, where the cathode part         includes a dielectric layer, and the anode part is provided with         a pair of circular through holes 15.     -   (S3) The dielectric layer is subjected to formation, where the         dielectric layer is provided on at least one side surface of the         cathode part.     -   (S4) A conductive polymer layer is formed on a surface of a         cathode part.     -   (S5) The conductive polymer layer is impregnated with conductive         colloidal graphite and dried to form a conductive carbon paste         layer.     -   (S6) The conductive carbon paste layer is impregnated with         conductive silver paste and dried to form a conductive silver         paste layer, such that a core 1 is obtained.     -   (S7) Steps (S1)-(S6) are repeated to obtain a plurality of cores         1.     -   (S8) The plurality of cores 1 are stacked and fixed in a case 3         to form a semi-finished capacitor.     -   (S9) A cover plate 4 is placed on the case 3 and sealedly         connected with the case 3 by parallel seam welding to produce         the stacked solid aluminum electrolytic capacitor 5.

Specifically, in step (S8), the plurality of cores 1 are stacked and fixed through the following steps.

-   -   (S8-1) An anode tongue portion 351 of an anode electrical         connection part 35 and a cathode tongue portion 361 of a cathode         electrical connection part 36 penetrate through a bottom of the         case 3. The anode tongue portion 351 is provided with a pair of         cylindrical positioning pins 3512, and the pair of cylindrical         positioning pins 3512 are in one-to-one correspondence with the         pair of circular through holes 15 on the anode part of the core         1.     -   (S8-2) The cathode tongue portion 361 is applied with a         conductive silver adhesive to bond to a cathode part 12 of a         first core 1, where the first core is a core of the plurality of         cores closest to the bottom of the case 3. The pair of         cylindrical positioning pins 3512 pass through the pair of         circular through holes 15 on an anode part 11 of the first core         1.     -   (S8-3) The step (S8-2) is repeated to complete the stacking of         the plurality of cores 1. Cathode parts 12 of the plurality of         cores 1 are bonded through the conductive silver adhesive         followed by curing to obtain a cathode of the stacked solid         aluminum electrolytic capacitor.     -   (S8-4) The rivet 2 is inserted into a hole of each of the pair         of cylindrical positioning pins 3512. The rivet 2, the pair of         cylindrical positioning pins 3512, and anode parts 11 of the         plurality of cores 1 are fixed through ultrasonic welding to         obtain an anode of the stacked solid aluminum electrolytic         capacitor.     -   (S8-5) An anode cavity of the case 3 is filled with an         insulating sealant and then cured.

Example 1

Referring to FIGS. 1-13 , an embodiment of the present disclosure provides a method for preparing the highly-reliable multilayer solid aluminum electrolytic capacitor, which includes the following steps.

-   -   (S1) A formed aluminum foil (3VF) is cut into an I-shaped         aluminum foil. The I-shaped aluminum foil consists of two wider         rectangles distributed at the ends and a narrower rectangular         connection part 13 in the middle, where an end of the I-shaped         aluminum foil is provided with a pair of circular through holes         15, and a length of the rectangular connection part 13 is 20% of         a total length of the first aluminum foil.     -   (S2) An insulating blocking adhesive is applied to upper and         lower surfaces and two sides of the rectangular connection part         13 of the I-shaped aluminum foil to form an insulating blocking         tape 14, so as to divide the I-shaped aluminum foil into an         anode part 11 and a cathode part 12. The anode part 11 is the         end of the I-shaped aluminum foil provided with the circular         through holes 15.     -   (S3) Three side surfaces of the cathode part of the I-shaped         aluminum foil are each provided with a dielectric layer, and the         dielectric layers are subjected to formation.     -   (S4) A conductive polymer layer is formed on a surface of a         cathode part.     -   (S5) The conductive polymer layer is impregnated with conductive         colloidal graphite and dried to form a conductive carbon paste         layer.     -   (S6) The conductive carbon paste layer is impregnated with         conductive silver paste and dried to form a conductive silver         paste layer, such that a core 1 is obtained.     -   (S7) Steps (S1)-(S6) are repeated to obtain four cores 1.     -   (S8) The four cores 1 are stacked and fixed in a case 3 to form         a semi-finished capacitor.     -   (S9) A cover plate 4 is placed on the case 3 and sealedly         connected with the case 3 by parallel seam welding to produce         the multilayer solid aluminum electrolytic capacitor 5.

The case 3 includes two first side plates 31, two second side plates 32, and a bottom plate 33. A length of the two first side plates 31 is larger than that of the two second side plates 32. A square open structure is enclosed by the two first side plates 31, the two second side plates 32, and the bottom plate 33. Inner side surface of the two first side plates 31 are each provided with one blocking plates 34, and two blocking plates 34 are arranged symmetrically. The two blocking plates 34 are connected to the bottom plate 33. The first side plate 31, the second side plate 32, the bottom plate 33 and the blocking plate 34 are all made of alumina ceramic. A height of each of the two blocking plates 34 is equal to a height of each of the two first side plates 31, and a width of each of the two blocking plates 34 is 20% of the width of the bottom plate 33. The two blocking plates 34 are configured to divide an inner cavity of the case 3 into an anode chamber and a cathode chamber matching the core 1 in shape. An anode electrical connection part 35 and a cathode electrical connection part 36 penetrates through the bottom plate 33. A rectangular metal ring 37 is fixedly arranged on an edge of an opening of the case 3. The rectangular metal ring 37 is made of a Kovar alloy.

The anode electrical connection part 35 includes an anode tongue portion 351, an anode connection portion 352, and an anode terminal portion 353 connected vertically in sequence. The anode tongue portion 351 includes rectangular portion 3511, and a side of the rectangular portion 3511 away from the anode connection portion 352 is provided with a pair of cylindrical positioning pins 3512 matching with the pair of circular through holes 15. The rectangular portion 3511 is embedded in and flush with an inner surface of the bottom plate 33. An anode ring protrusion 3521 is provided at a middle of the anode connection portion 352. The anode terminal portion 353 is embedded in and flush with the outer surface of the bottom plate 33.

The cathode electrical connection part 36 includes a cathode tongue portion 361, a cathode connection portion 362, and a cathode terminal portion 363 connected vertically in sequence. The cathode tongue portion 361 is rectangular, and is embedded in and flush with the inner surface of the bottom plate 33. A cathode ring protrusion 3621 is provided at a middle of the cathode connection portion 362. The cathode terminal portion 363 is embedded in and flush with the outer surface of the bottom plate 33. The anode electrical connection part 35 and the cathode electrical connection part 36 are made of copper or a copper alloy, and the surface of the anode terminal portion 353 and the cathode terminal portion 363 exposed out of the case 3 are also provided with a tin coating.

In this embodiment, a ceramic case with integrated embedded metal pins is adopted, and a protruding structure is provided on the part of the metal pins located inside the ceramic case, which is configured to extend the water vapor path and increase the resistance to moisture.

The four cores 1 are stacked and fixed through the following steps.

-   -   (S8-1) A conductive silver adhesive is applied to the cathode         tongue portion 361, and the cathode tongue portion 361 is bonded         to a cathode part 12 of a first core 1, where the first core 1         is the core of the four cores closest to the bottom plate 33. A         pair of circular through holes 15 on an anode part 11 of the         first core 1 is sleeved on a pair of cylindrical positioning         pins 3512 of an anode tongue portion 351.     -   (S8-2) The step (S8-1) is repeated to complete stacking of the         four cores 1. Cathode parts 12 of the four cores 1 are bonded         and cured through the conductive silver adhesive to obtain a         cathode of the stacked solid aluminum electrolytic capacitor.     -   (S8-3) The rivet 2 is inserted into a hole of each of the pair         of cylindrical positioning pins 3512. The rivets 2, the pair of         cylindrical positioning pins 3512, and anode parts 11 of the         four cores 1 are fixed through ultrasonic welding to obtain an         anode of the stacked solid aluminum electrolytic capacitor.

The rivet 2 includes a circular rivet head 21 and a cylindrical rivet pin 22 connected to each other, and the cylindrical rivet pin 22 matches with the circular through hole 15. The diameter of the circular rivet head 21 is larger than the diameter of the cylindrical rivet pin 22, and the end of the cylindrical rivet pin 22 away from the circular rivet head 21 is tapered. The tapered end of the rivet 2 is driven into the hole of the cylindrical positioning pin 3512, and the rivet is made of copper or a copper alloy

-   -   (S8-4) An anode cavity of the case 3 is filled with an         insulating sealant and then cured.

The cover plate 4 is made of a Kovar alloy. The edge of one side of the cover plate 4 near the case 3 is provided with a protrusion 41 matching with the rectangular metal ring 37, and the cover plate 4 is fixed through fitting between the protrusion 41 and the rectangular metal ring 37 by welding.

In this embodiment, an outer surface of the bottom plate 33 is the surface away from the opening direction of the case 3, and the inner surface of the bottom plate 33 is the surface close to the opening direction of the case 3.

Comparative Example

Provided is a method for preparing a solid aluminum electrolytic capacitor, which includes the following steps.

-   -   (S1) A formed aluminum foil (3VF) is cut into a long-stripe         shaped aluminum foil.     -   (S2) An insulating blocking adhesive is applied to the         long-stripe shaped aluminum foil to divide the long-stripe         shaped aluminum foil into an anode part and a cathode part. The         area of the cathode part in this embodiment is the same as the         area of the cathode part in Example 1.     -   (S3) Three side surfaces of the cathode part of the long-stripe         shaped aluminum foil are each provided with a dielectric layer,         and the dielectric layers are subjected to formation.     -   (S4) A conductive polymer layer is formed on a surface of the         cathode part.     -   (S5) The conductive polymer layer is impregnated with conductive         colloidal graphite and dried to form a conductive carbon paste         layer.     -   (S6) The conductive carbon paste layer is impregnated with         conductive silver paste and dried to form a conductive silver         paste layer, such that a core is obtained.     -   (S7) Steps (S1)-(S6) are repeated to obtain four cores.     -   (S8) The four cores are stacked and fixed on the front and back         sides of the external flat lead frame. Specifically, the anode         part of the core is electrically connected to the external lead         frame by welding, and the cathode part of the core is         electrically connected to the external lead frame through a         conductive silver glue, so as to form a core package.     -   (S9) After the core package is encapsulated in epoxy resin and         cured, the leads extending out of the resin case are bent to         form pins to obtain the solid aluminum electrolytic capacitor.

Electrical performance of 2V330 μF solid aluminum electrolytic capacitors produced in the Example 1 and Comparative Example are tested, and the data are shown in Table 1.

TABLE 1 Electrical performances of solid aluminum electrolytic capacitors in Example 1 and Comparative Example. Equivalent Capacitance change Leakage current series rate after steady-state after steady-state Leakage resistance damp heat test damp heat test current (ESR) (85° C./ (85° C./85% RH, Samples (μA) (mΩ) 85% RH, 500 h) 500 h) (μA) Example 1 10.1 5 11.6% 87 Comparative 26.4 9 43.3% 394 Example

The core of this application is to adopt an I-shaped capacitor core. The I-shaped capacitor core is assembled into a ceramic case provided with an I-shaped inner cavity and integrated embedded pins, and then sealedly connected with a cover plate to produce a highly-reliable and surface-mountable multilayer solid aluminum electrolytic capacitor, which is different from the common multilayer solid aluminum electrolytic capacitor. Specifically, the common multilayer solid aluminum electrolytic capacitor is encapsulated with organic materials, and the encapsulation material directly touches the core. On the contrary, the multilayer solid aluminum electrolytic capacitor provided herein is hermetically encapsulated with inorganic materials by using a ceramic case and a cover plate, and a gap exists between the ceramic case and the core.

Moreover, the common multilayer solid aluminum electrolytic capacitor uses an external lead frame (lead wire) to stack the cores on the anode and cathode tongues of the lead frame piece by piece, so as to lead out the anode and cathode, where the external terminals are formed by bending the leads exposed on the outside of the resin encapsulated case to the outer surface of the product. In contrast, in this application, lead components are pre-integrated in the encapsulated case to replace the pin forming process after encapsulation.

As can be seen from the electrical performance data, compared with the comparative example, the multilayer solid aluminum electrolytic capacitor produced in Example 1 has lower leakage current, lower ESR, better air tightness and better moisture resistance.

It should be understood that as used herein, the terms, such as “coaxial”, “bottom”, “end”, “top”, “middle”, “other end”, “upper”, “side”, “top”, “inside”, “front”, “top”, “inside”, “front”, “center”, and “two ends” are used to illustrate orientation or positional relationships in the accompanying drawings, and are merely intended to facilitate and simplify the description of this application, but not indicate or imply that the device or element referred to must have a particular orientation or be constructed and operate in a particular orientation. Therefore, these terms should not be considered as limitations for the present disclosure.

Unless otherwise expressly specified and limited, as used herein, the terms “mounting”, “setting”, “connecting”, “fixing”, and “screwing” shall be understood in a broad sense. For example, it may refer to a fixed connection, a detachable connection or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; and communication or interaction between two elements. Unless otherwise expressly limited, the specific meaning of the above terms in the context of the present disclosure can be understood by one of ordinary skill in the art depending on the specific circumstances.

Although the present disclosure has been illustrated and described in detail above, it should be understood that one of ordinary skill in the art can still make various variations, changes, modifications and replacements to the embodiments disclosed herein. It should be noted that those variations, changes, modifications and replacements made without departing from the principle and spirit of the present disclosure shall still fall within the scope of the present disclosure defined by the appended claims. 

What is claimed is:
 1. A method for preparing a stacked solid aluminum electrolytic capacitor, comprising: (S1) cutting a formed aluminum foil to obtain an I-shaped aluminum foil; wherein the I-shaped aluminum foil comprises a rectangular connection part; (S2) dividing the I-shaped aluminum foil into an anode part and a cathode part by applying an insulating blocking tape to the rectangular connection part, wherein the cathode part comprises a dielectric layer, and the anode part is provided with one or more circular through holes; (S3) subjecting the dielectric layer to formation; (S4) forming a conductive polymer layer on a surface of the cathode part; (S5) impregnating the conductive polymer layer with conductive colloidal graphite followed by drying to form a conductive carbon paste layer; (S6) impregnating the conductive carbon paste layer with a conductive silver paste followed by drying to form a conductive silver paste layer, such that a core is obtained; (S7) repeating steps (S1)-(S6) to obtain a plurality of cores; (S8) stacking and fixing the plurality of cores in a case to form a semi-finished capacitor; and (S9) placing a cover plate on the case; and sealedly connecting the cover plate with the case to produce the stacked solid aluminum electrolytic capacitor.
 2. The method of claim 1, wherein step (S8) comprises: (S8-1) penetrating a bottom of the case with an anode electrical connection part and a cathode electrical connection part, wherein the cathode electrical connection part is applied with a conductive silver adhesive, and the anode electrical connection part is provided with one or more cylindrical positioning pins, and the one or more cylindrical positioning pins are in one-to-one correspondence with the one or more circular through holes on the anode part of the core; (S8-2) bonding the cathode electrical connection part with a first cathode part of a first core, and passing the one or more cylindrical positioning pins through the one or more circular through holes on a first anode part of the first core; (S8-3) repeating step (S8-2) to complete the stacking of the plurality of cores; and bonding cathode parts of the plurality of cores through the conductive silver adhesive followed by curing to obtain a cathode of the stacked solid aluminum electrolytic capacitor; and (S8-4) inserting a rivet into a hole of each of one or more cylindrical positioning pins, and fixing the rivet, the one or more cylindrical positioning pins, and anode parts of the plurality of cores through ultrasonic welding to obtain an anode of the stacked solid aluminum electrolytic capacitor.
 3. The method of claim 1, wherein the dielectric layer is provided on at least one side surface of the cathode part.
 4. The method of claim 1, wherein the cover plate is sealedly connected with the case by parallel seam welding.
 5. The method of claim 2, wherein the case comprises an anode chamber and a cathode chamber respectively matching the anode part and the cathode part of the core in shape.
 6. The method of claim 5, further comprising filling the anode chamber of the case with an insulating sealant followed by curing. 